1. Field of the Invention
The present invention relates to image processing of an image obtained by radiographic imaging. More particularly, the present invention relates to a technique useful for determining a processing method of image processing.
2. Description of the Related Art
According to the advance of digital technology, two-dimensional X-ray sensors (e.g., flat panel detector (FPD)) which can output X-ray images as digital data are widely used these days. X-ray imaging for medical care is generally used in the fields of medical care diagnosis. Thus, the demand for digital image processing appropriate for diagnosis is increasing.
Japanese Patent Application Laid-Open No. 61-68031 discusses a method for applying a predetermined image processing algorithm to image processing by inputting an imaging portion of a subject or information of the imaging method. According to this method, digital image processing appropriate for diagnosis can be performed for the images based on the input information.
Further, the demand for a technique that can realize general image processing without inputting image processing parameters for each image is also increasing.
Japanese Patent Application Laid-Open No. 2006-087934 discusses a method for removing portions not necessary for the diagnosis from the image by the image analysis is performed. The unnecessary portions are, for example, regions other than the irradiation field region necessary for the diagnosis and the portions where the sensor is directly irradiated by the X-ray. The remaining portions are subjected to the histogram analysis and image processing parameters are obtained.
When imaging of an X-ray moving image is performed, the imaging range is continuously changed. Thus, narrowing of X-rays by a collimator, presence/absence of the region directly exposed to the X-ray, shapes and positional relation of characteristic structures of the body (e.g., lung field, bone region), and the size of the characteristic structures in the image are continuously changed. Since images of a great variety are taken, it is convenient if general-purpose image processing can be used for the processing of the images.
Further, since it is necessary to reduce the amount of emission of the X-rays, an image of desirable quality cannot always be obtained. Thus, importance of image processing such as gradation processing, dynamic range compression processing, noise reduction processing, and edge enhancement processing is increasing.
However, since the information needs to be input for each image, according to the input method of information regarding an imaging portion and imaging method discussed in Japanese Patent Application Laid-Open No. 61-68031, the method cannot be generally applied to various images.
Further, according to the method discussed in Japanese Patent Application Laid-Open No. 2006-087934, extraction of regions other than the irradiation field and the regions directly irradiated by X-ray according to identification processing can be performed only to a portion of an image whose parameters are determined. Thus, not all images can be processed according to the method.